Targeted expression of therapeutic genes to the angiogenic vasculature would provide a valuable treatment option for a number of disorders, such as ischemic heart disease (Malin, D., et al., Curr Opin Pharmacol, 7:158-163 (2007)), diabetic retinopathy (Andreoli, C. M., et al., Curr Opin Ophthalmol, 18:502-508 (2007)), rheumatoid arthritis (Khong, T. L. et al., Angiogenesis, 10:243-258 (2007)), malignant tumors (Kerbel, R. S., N Engl J Med, 358:2039-2049 (2008)), and peripheral artery disease (Jones, W. S., et al., Curr Opin Cardiol, 22:458-463 (2007)). To date, a number of targeted gene-delivery strategies have been developed to express therapeutic genes in angiogenic vessels (Brandwijk, R. J., et al., Trends Mol Med, 13:200-209 (2007)). Focus has been placed on the improvement of delivery vehicles, both viral and non-viral, as well as on the isolation of endothelial cell (EC)-specific promoters from genes, such as vascular endothelial growth factor receptors (VEGF-R11VEGF-R2) (Nicklin, S. A., et al., Hypertension, 38:65-70 (2001); Savontaus, M. J., et al., Gene Ther, 9:972-979 (2002)), intercellular adhesion molecule-2 (ICAM-2) (Nicklin, S. A., Hypertension, 38:65-70 (2001)), von Willebrand factor (Nicklin, S. A., et al., Hypertension, 38:65-70 (2001)), and preproendothelin 1 (PPE) (Varda-Bloom, N., Gene Ther, 8:819-827 (2001); Greenberger, S., J Clin Invest, 113:1017-1024 (2004)). However, except for the PPE promoter, these promoters are not specific for angiogenic blood vessels. Unlike these pan-EC promoters, the mouse activin receptor-like kinase 1 (Alk1; Acvrl1) promoter induces transgene expression specifically in ECs of newly forming and remodeling arteries that feed ischemic lesions and developing tumors.
ALK1 is one of the type I receptors for the transforming growth factor β (TGF-β) superfamily ligands. Using Alk1+/lacZ reporter knock-in mice it was established that Alk1 gene expression is detected in a transient manner in the arteries feeding ischemic tissues (Seki, T., et al., Circ Res, 93:682-689 (2003)). The Alk1 gene regulatory region was isolated as a 9.2 kb Alk1 regulatory fragment (Seki, T., et al., Circ Res, 94:e72-77 (2004)). The transgenic mouse line with this 9.2 kb fragment, Tg(Alk1-lacZ), virtually recapitulated the reporter gene expression pattern observed in Alk1+/lacZ mice. The viral gene transfer vectors used in gene therapy, however, have limited payload capacities, and the 9.2 kb fragment is too large to be utilized in most of the vectors (Thomas, C. E., et al., Nat Rev Genet, 4:346-358 (2003)).
Therefore, it is an object of the invention to provide nucleic acid constructs that targets expression of therapeutic genes to the angiogenic vasculature.
It is another object of the invention to provide compositions and methods for treating ischemic heart disease, diabetic retinopathy, rheumatoid arthritis, malignant tumors, and peripheral artery disease.
It is an object of the invention to provide an isolated nucleic acid containing regulatory elements sufficient to target gene expression to the angiogenic vasculature.
It is yet another object to provide a transgenic host containing a nucleic acid construct that targets expression of therapeutic genes to the angiogenic vasculature.